Device for regulating the flow in a drainage siphon tube

ABSTRACT

A device for regulating the flow in a drainage siphon tube, includes a rigid tube connected to the outlet end of the siphon tube. The rigid tube is placed on a brace such that it can oscillate around a horizontal axis by means of a counter-weight. Pivoting upward of the tube is limited by a high block stop and pivoting downward is limited by a low block stop in such a way that when the siphon tube is delivering above its critical point, the tube is tilted downward, resting on the lower block stop and when the critical outflow is reached, the tube empties itself and comes to rest against the higher block stop by means of the counterweight. An increase in the pressure at the inflow end of the siphon tube results in a rise of the water in the rigid tube until the imbalance makes it pivot to the downward tilted position where it rests on the low block stop and delivery higher than the critical point ejects the gas bubbles accumulated at the high point of the siphon tube.

BACKGROUND OF THE INVENTION

The present invention relates to a device for regulating the flow in asiphon tube assembly. More particularly, it relates to a device fittedto the outlet end of a drainage siphon tube, allowing it to functioncontinuously, or intermittently, with an overflow superior to a definedminimal critical outflow determined by on-site parameters.

In my earlier patent, U.S. Pat. No. 4,717,284, I disclose a device fordraining soils in depth, the subject matter of which is incorporatedherein.

French Patent No. 2,593,203 and European Patent Application No. EP 0 230918 disclose a drainage siphon device capable of functioningcontinuously, and in an autonomous way, without the risk of unpriming,as a result of which there is no need for repeated care or systematicsurveillance. While satisfactory in the great majority of situationsencountered in the field, it happens, however, that the functioning ofthis device is, under certain circumstances, problematic where the waterto be siphoned comprises a significant amount of dissolved gases. Whenthe water rises within the tube forming the siphon, its pressuredecreases and part of the gas is freed in the form of bubbles. Thesebubbles are drawn along the water flow as long as the latter remainsadequately strong. However, below a certain minimum outflow, called a"critical point" the bubbles are no longer drawn along but instead theyall rise to the highest point of the siphon, meet there and form a largebubble by coalescence.

Tubes of interior diameter superior to the 10 mm and those whoseinterior diameter is less than 6 mm present noticeably differentbehaviors.

In the last case (6 mm and less) when the critical point is reached, thebubbles take up or occupy the entire cross section of the siphon tube,as a result of which outflow is stopped. At the same time, thecontinuous feed flow from the borehole in which the drain is placedresults in an increase in the water level within the drain and thus, anincrease in the hydrostatic pressure. This increased pressure reaches apoint where it is strong enough to completely eject the large bubblewhich has accumulated at the highest point, following which the siphontube works normally again until it enters a new "stopping phase", causedby reaching the "critical point" again and the formation of anotherbubble.

For tubes of a diameter larger than approximately 10 mm, the bubblestagnating at the highest point of the siphon tube does not at first,take up the whole cross-section of the tube and allows for a certaintime a certain outflow until, by coalescence, it also is large enough tototally stop the outflow. Here too, the hydrostatic pressure increasesin the borehole until it is strong enough to eject the bubble and allowthe outflow to resume. However, the pressure necessary to eject thebubble can, in certain situations be unacceptable or at leastundesirable. As discussed in the above patents, this problem can besolved by equipping the drain with several siphon tubes of differentdiameters, working simultaneously or in turn, according to temporaryconditions. However, this solution requires fittings which can becostly, cumbersome and complicated due to the several siphon tubesinvolved.

SUMMARY OF THE INvENTION

Accordingly, it is an object of the present invention to overcome thesedisadvantages in the actual state of the art by providing a device thatcan work continuously and in an autonomous way with no risk ofunpriming, which has no external energy requirements and which needs norepeated care or systematic surveillance.

It is a more particular object of the present invention to provide sucha device which allows the automatic interruption of siphoning when theoutflow is below the "critical point", and the automatic resumption ofsiphoning under a hydrostatic pressure defined for the site drained.

Certain of the foregoing and related objects are achieved in a devicefor regulating the flow in a drainage siphon tube assembly of the typehaving a siphon tube with an inlet end and an outlet end, and at leastone drain support tube arranged within a drainage borehole having alower end defining a reservoir with a top lip disposed at the samealtitude level as said siphon tube outlet end. The device includes asupport disposed adjacent the siphon tube outlet end, means forpivotably mounting the outlet end of the siphon tube on the support forpivotable movement about a horizontal axis, and a rigid tube having onefree end and an opposite end coupled to said outlet end of the siphontube. A counterweight cooperates with the outlet end of the siphon tubeto cause the free end of the rigid tube to pivot upwardly to apredetermined high point when there is no flow and to alternativelypivot downwardly to a predetermined low point when there is a flow.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will become apparentfrom the following detailed description considered in connection withthe accompanying drawings. It is to be understood, however, that thedrawings are designed as an illustration only and not as a definition ofthe limits of the invention.

In the drawings, wherein similar reference characters denote similarelements throughout the several views:

FIG. 1 is a schematic sectional side view of a drainage installationfitted with a device according to the invention; and

FIG. 2 is an enlarged schematic sectional view of a portion of thedevice shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following, the invention is described within an example of thedrainage situation of a slope or a site where the land is likely toslide and the drain is placed in a borehole. It should be evident thatthe example is not restrictive and that the invention may findapplication in many other cases, according to site particularities, asis evident to one skilled in the art.

Thus, turning now in particular to FIG. 1, the drain represented isvertical but any gradient giving a descending penetration of the draintoward the inflow end is possible without changing the workingprinciple. The drain is shown within a borehole but, as stated above,could also be driven, vibrated or cast, according to known techniques.It comprises a first tube 1, for example made of plastic materialsuitable for this use. The section of tube 1 in contact with water isperforated so that it acts as a strainer when performing its drainingfunction. Preferably, tube 1 is closed off at its lowest end by a plug 2to avoid the entry of particles into the end of the drain. If desired,filter material 3 may also be placed between the walls of the boreholeand tube 1.

A second tube 20 made also, for example, of a suitable plastic materialis placed within tube 1. The mid-section 4 of tube 20 is perforated 4 sothat it too acts as a strainer; it can also be protected by filtermaterial or a second filter (not shown). The lower end of second tube 20is advantageously closed and its sides imperforate to form a reservoiror tank 5. The top section 6 of tube 20 has imperforate walls 6 and endsin, at least one radial side outlet 7 and, optimally, according to whatis practical due to site conditions, four radial outlets 7 arranged in across to allow access to and provide mechanical support for theoperating end of a siphon tube 11. Top section 6 is best placed in awatch hole. From this watch hole, a pipe 9 made of an appropriateplastic material extends to another watch hole called an outlet watchhole 10. Pipe 9 is kept below the frost line to shield it from climaticinfluences.

An end 12 of siphon tube 11 extends permanently into second tube 20 withits lower end in reservoir 5. From reservoir 5 it extends upwardlythrough strainer section 4 and up through the imperforate top section 6and out of one of the radial outlets 7 at which point tube 11 has anintermediate section which is nearly horizontal. The following sectionof tube 11 descends through a tube 9, disposed preferably below thefrostline and shielded from climatic influences, to an outlet housingthat is disposed on the same level as the top part or lip of reservoir 5so that the siphon can work without ever emptying the reservoir.

However, to overcome the disadvantages discussed above due to theevolution and the coalescing of bubbles at the highest point of thesiphon tube 11 the end 13 of siphon tube 11 is set up in an outlet watchhole 10 of the siphon tube 11 on the same level as the top lip ofreservoir 5. As seen best in FIG. 2, it is hooked up either directly or,preferably, by a rotating coupling 19 to a rigid tube 14. This rigidtube 14 can pivot about a horizontal axis or axle 15, held up by asupport or brace 20 and counterbalanced by the action of a counterweight16. The pivot travel or run of the tube is limited above and below by ahigh block stop 17 and a low block stop 18. The siphon can be primed byinjecting water into the end of the rigid tube 4 until all the air hasbeen cleared out of the siphon tube 11 and the water within the linepasses through outlet end 13 of siphon tube 11. Then, upon stopping theinjection of water, and the water pressure within the drain with regardto the outlet end 13 of the siphon induces the siphoning function of thedrainage system. Preferably, the end 13 of siphon tube 11 is equippedbefore reaching the level of the rotation axis 15, with a flexibleU-shaped member which assists the free up or down movements of the rigidtube 14. With the weight of the water in the rigid tube 14 being themotive force with regards to counterweight 16, this tube comes to restagainst the lower block stop 18. The siphon then has an outflow superiorto the critical point mentioned above.

When the flow slackens and reaches the critical point, the flow withintube 14 begins to trickle, i.e., it flows with a free surface, and bymeans of predetermined equilibration, counterweight 16 unbalances tube14 when it is practically empty. The free end of tube 14 then rises andstrikes the top block stop 17. The siphon then stops delivering. Ifnormal feeding of the drain allows a rise in the water, it will beaccompanied by a rise in the water within rigid tube 14. The weight ofthe water contained in tube 14 will then be the motive force withregards to counterweight 16 and the tube will again come to hit thelower block stop 18. Given an appropriate positioning of the upper andlower block stops 17, 18 relative to the length of the rigid tube, theunbalancing will occur at a pressure in the drain allowing outflowbeyond the critical point until a new stopping period begins.

After priming, as described above, water entering the drain atatmospheric pressure, contains a certain proportion of dissolved gases.When the water rises upwardly in siphon tube 11 its pressure slackensand gas bubbles appear. As long as the outflow is rapid enough, thesebubbles are evacuated by the water flow. However, at the critical point,the bubbles are no longer evacuated. At the same time, as rigid tube 14empties itself, bubbles in siphon tube 14 cause it to tip over. Aftertipping of tube 14, the new hydraulic pressure between the water levelin the drain and the bottom end of tube 14 will produce a turbulentoutflow within siphon tube 11 which will carry along with it thestationary bubble at the high point of siphon tube 11. The volume ofwater evacuated from the drain by siphon tube 11 during the turbulentoutflows must absolutely be superior to the volume of the siphon tube inorder to clear all the bubbles.

From the above, it is clear that, as a result of the end 12 of thesiphon tube 11 being constantly submerged in reservoir 5, the siphontube can never become unprimed from that end, even when the borehole iscompletely empty, e.g., during a dry spell, since the water level alwaysstays at least up to the top lip of the reservoir 5. In this case, thesiphon will, of course, not function since there is no water to drain,but as soon as new water infiltration enters the drain and allows, byinduced pressure, the rise of the water in tube 14 and, consequently,its downward tipping, the siphon will be reactivated. The entry of airinto the end of tube 14 has no harmful effect since, when it happens, itinitiates upward tipping of the tube around axis or axle 15.

It should be noted that the device described can be used to set uindividual drains or parallel drains with a common outlet or differentoutlets in a structure suitable to any site and complementary with otherdrainage systems. Moreover, for one drainage system, several siphoningtubes of different diameters may be set up, each hooked up to anindividual reservoir 5 and an individual tube 14, adapting the geometryof the system to the outflows to be extracted and, thus to theaquiferous configuration of any site.

Thus, while only one embodiment of the present invention has been shownand described, it is obvious that many changes and modifications ma bemade thereunto without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A device for regulating the flow in a drainagesiphon tube assembly of the type having a siphon tube with an inlet endand an outlet end, and at least one drain support tube arranged within adrainage borehole having a lower end defining a reservoir with a top lipdisposed at the same altitude level as said siphon tube outlet end,comprising:a support disposed adjacent said siphon tube outlet end;means for pivotably mounting said outlet end of said siphon tube on saidsupport for pivotable movement about a horizontal axis; a rigid tubehaving one free end and an opposite end coupled to said outlet end ofsaid siphon tube; and a counterweight cooperating with said outlet endof said siphon tube to cause the free end of said rigid tube to pivotupwardly to a predetermined high point when there is no flow and toalternatively pivot downwardly to a predetermined low point when thereis a flow.
 2. The device according to claim 1, wherein said siphon tubeoutlet end defines an outlet, and said siphon tube additionally includesa flexible U-shaped member coupled thereto adjacent said outlet endthereof immediately below said outlet.
 3. The device according to claim1, additionally including a high block stop and a low block stopdisposed adjacent said free end of said rigid tube, said high block stopbeing positioned to limit upward pivoting of said free end to saidpredetermined high point and said lower block stop being positioned tolimit downward pivoting of said free end to said predetermined lowpoint.
 4. The device according to claim 1, additionally including arotatable coupling for coupling said outlet end of said siphon tube tosaid rigid tube.
 5. The device according to claim 1, wherein said deviceis mounted within an outlet housing accessible by a watch hole.